In conventional fuel injection systems (FI systems), a fuel injector injects a predetermined amount of fuel into an air-intake passage connected to an engine under control of an ECU (electronic control unit). In some vehicles including such FI systems, the ECU causes the fuel injector to stop fuel injection to forcibly stop running of the engine, when a tilting sensor detects that a body thereof is tilted a specified angle or larger.
Typically, the tilting sensor is positioned in the vicinity of a center of gravity of the body to precisely detect that the body is tilted. In the vicinity of the center of gravity of the body, relatively bulky components such as the engine, a fuel tank, and an air cleaner box are disposed. If the tilting sensor is positioned in the vicinity of the center of gravity of the body, space for the other components is reduced, requiring volumes of the other components to be smaller or have intricate shapes. Generally, tilting of the vehicle occurs infrequently, and therefore the tilting sensor is activated infrequently. For these reasons, it is undesirable for the tilting sensor to occupy the space in the vicinity of the center of gravity of the body. In addition, brackets and electric wire are needed to mount the tilting sensor in the vehicle, increasing structural members, the number of components, and the overall manufacturing cost of the vehicle.